linux-kernel - Re: [PATCH v3] tpm_crb: request and relinquish locality 0

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Date:   Fri, 17 Mar 2017 11:11:16 -0600
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     Jerry Snitselaar <jsnitsel@...hat.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jarkko Sakkinen <jarkko.sakkinen@....fi>,
        tpmdd-devel@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org, gang.wei@...el.com,
        Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] tpm_crb: request and relinquish locality 0

On Fri, Mar 17, 2017 at 10:00:41AM -0700, Jerry Snitselaar wrote:

> > Changing the return value to -EBUSY was a stupid mistake from my side.
> >
> > I'll try revise this a bit in a way that the API will allow positive
> > value for stating that the given locality has been already taking.
> 
> Is there a big performance hit with requesting and releasing locality?
> If instead it just released it when release_locality is called I think
> the changes are pretty minor.

If you can measure please let us know :)

This is all very old it may not actually make any sense..

.. and as I said earlier if we want to 'cache' the locality for
performance then the core code should do it.

I kinda thought the point of releasing the locality was to allow other
platform things to access the TPM, so I'm confused why TIS wouldn't
always release it as well..

Jason